Abstract: As an important blue carbon ecosystem, mangrove forests are among the most effective natural systems for carbon sequestration in combating climate change. Climate change provides an opportunity for the northward expansion of mangroves. Yet, their capacity of carbon sequestration is poorly understood. With long-term eddy covariance technique, we investigated the daily and seasonal dynamics of net ecosystem exchange (NEE) of young northward-afforested mangroves in southern Zhejiang Province and explored the main driving factors. The results showed that NEE of the northward-afforested mangroves demonstrated a U-shaped pattern on diurnal scale. There was a strong seasonality of NEE, which peaked in summer and decreased as temperature cools. NEE was strongly positively correlated with photosynthetically active radiation and wind speed, but was negatively correlated with air pressure and vapor pressure deficit. Based on the annual cumulative data of eddy NEE, the carbon sequestration capacity of the young northward-afforested mangroves (3 years old) was 291 g C·m^-2·a^-1, reflecting its potential as a carbon sink.

Key words: northward-afforested mangrove, Kandelia obovata, eddy covariance technique, net ecosystem exchange, environmental factor